#include <stdio.h>
#include <string.h>

int main()
{
    FILE* f = fopen("bit.txt", "w+");
    if(f < 0){
        perror("fopen\n");
        return 1;
    }


    const char* str = "linux easy\n";
    fwrite(str, 1, strlen(str), f);
    printf("fileno = %d, success\n", f->_fileno);
    fclose(f);
    return 0;
}
